A power management system applied to an information handling system, e.g. CPU, will adjust performance states according to the states of the information handling system so as to improve efficiency. For example, a core of the CPU may operate at various performance states or levels, so-called P-states, namely from P0 to PN. In general, the P0 performance state may correspond to the highest performance state than can be requested by an OS (Operating System), and PN performance state may correspond to the lowest performance state. In addition, sleep state of the core also has several levels, so-called C-states, namely from C0 to C10, while C10 refers to the deepest, lowest power sleep state. Accordingly, the power management system may specify different power consumption states, generally referred to as PS-states, PS0, PS1 to PSN states. When the core is active, the power management system runs at a PS0 state, and when the core sleeps, it may be placed in a low power state PS4.
Modern standby mode is used by a computer to mimic cell phone behavior where the device appears to be “off”, but actually is still “connected”. Correspondingly, the core enters the C10 state and the power management system is placed in PS4 state when the CPU is in deep sleep state, i.e., modern standby mode. Intel CPU with the core and power management system integrated, which is widely applied in computers, exits the modern standby mode (PS4/C10 state), and enter its high power turbo state (PS0/C0 state) to complete tasks as quickly as possible. This ‘turbo’ state consumes unnecessary power as the tasks are not complex during exiting the modern standby mode.